Combustion chamber



C. SEIPPEL GOMBUSTION CHAMBER Dec. 30, 1941.

Filed Sept. '7, 1940 l Patented Dee'. 3o, 1941 UNITED STATE COMBUSTION CHAMBER Claude Seippel, Ennetbaden, Switzerland, asslgn- A or to Aktiengesellschaft` Brown, Boveri & Cle., 7/

Baden, Switzerland Application september 7, 1940, serial No. 355,877 In Switzerland September 29, 1939 Claims. (Cl. 263-19) This invention relates to combustion chambers and particularly to metal combustion chambers for the production of heating or power gases at moderate temperatures.

Gases at moderate temperatures are frequenter supporting wall and an inner wall of heatly needed for heating and power purposes. With suitable provision 'such gases can be produced in combustion chambers constructed entirely of metal, that is, without requiring the use of ceramic construction materials. The desired moderate temperatures l'(about 400-700" C.) are not obtained by Vburning the fuel with a very large excess of air since too large excesses of air bring about poor combustion, smoking and easy extinguishing of the flame. One must, on the contrary, select the most favorable, that is, a usually quite low, excess of air "and mix the com-v f bustion gases gradually with so much air that the desired heating or power gas temperature is obtained. In spite of the high temperature which the flame develops with low excess of air, the combustion chamber can be constructed of metal and the use of any special coolingI agent, such as water, can be eliminated if one uses for cooling the walls of the combustion chamber the.

gas is conducted which cools the inner wall, isv lthereafter mixed with the combustion gases and forms in admixture with the combustion gases the heating or power means of moderate temperature. l

In order to obtain a suitable cooling of the inner wall, it is necessary to pass the cooling medium Vpast the wall with a high velocity so that its heat absorbing capacity becomes large. Moreover, the inner combustion chamber wall which forms one side ofthe cooling medium passage must be so constructed that even under the effect of heat expansion the uniform distribution of the cooling medium and of its velocity is maintained. While with small combustion chambers the construction of the inner wall as a simple cylinder provided with radial projections is satisfactory, it has been found that with larger combustion chambers, for example, handling more than fourmillion kilogram calories per hour, special precautions must be taken.

The principal purpose of the present invenresistant metallic plates between which walls i cooling air or cooling gases are conducted, the inner wall being formed of a plurality of short channels through ,which the cooling agent, flowing out of the space between the inner and outer combustion -chamber walls, passes with a high velocity.

. By the subdivision of the inner wall into a plurality of portions, it becomes possible to compensate for changes in form due to heat expansion so that thev required channel cross-section area for a given amount of cooling agent is maintained and also the length of the stream path of each cooling channel is so short that the flow resistance to be overcome is kept at a minimum. Particular care must be taken that in certain types of uses, for example, for gas turbine combustion chambers, the pressure drop of the cooling air is only very small in order that too much efficiency is not 10st in the wall cooling.

The invention will be more' particularly described with reference to the accompanying drawing showing various embodiments of ithe principles of the invention. In the drawing:

Fig. 1 is an elevation in partial section of the principal portion of a combustion chamber for a gas turbine; and s Figs. 2 to l are fragmentary sections vshowing the details of variousv constructional modifications of the invention.

In the gas turbine combustion' chamber of Fig. 1, the air is introduced at I and divides itself in the combustion chamber head 2 into two portions. One portion passes as combustion air to the actual combustion chamber 4, together with the fuel introduced through the fuel nozzle 3. The greater portion of the air, however, is cooling air which flows into space 5 between the inner combustion chamber wall 6 and the outer combustion chamber wall 1. The inner combustion wall 6 comprises a number of cone-shaped rings 6a of metal plate which overlap each other in such a way as to provide between the conical rings annular passages 8 through whichr the cooling medium flows with high velocity out of space 5.

The individual conical rings are so suspended j from the outer wall 'l that they may freely expand. As is shown in Figs. 2 and 3, the rings 6amay be supported by means of pivotally mounted link members l0 or, as in Fig. 4, by means ring members 6a may be supported for free` expansion by means of radially projecting plates I2 riding in guiding slots I|` on the inner surl face of the outer wall 1.

The spacing of the adjacent cones 6a from each other, and thereby their centering and maintenance of the channel section, is provided by ribs I3. It is desirable to have the individual conical rings overlap to such an extent that the inner r combustion chamber wall consists over its entire length of channels closed on both sides so that the opposite sides of the portions of the rings in contact with the flame are everywhere washed by rapidly flowing cooling medium. With combustion chambers which are only moderately burdened, particularly with fuels of low radiation value, the overlapping may be less extensive as it may be assumed that the heat conductivity of the metal plate will be suiiicient to keep cool also those portions of the wall past which the cooling agent iiows at a moderate velocity. In every case the cooling medium has only a low velocity in space 5 in order to avoid too large pressure drops. A particular advantage of the method of construction of the invention consists in the possibility of supplying the cooling medium at low velocity and only accelerating it for the short distance` where it is required to exert its cooling action.

In order to better avoid warping of the inner wall by high heat., the ring members 6a can themselves be formed of a plurality of overlapping conical rings I4, as shown in Fig. 5. Also a subdivision of the individual conical rings is possible wherein the shingle-like overlapping is provided not only from ring to ring but also from ring segment to ring segment. Instead of the strictly conical form the ring members may be given the equivalent step-down cylindrical form, as is shown by members I5 in Fig. 7.

I claim:

1. A combustion chamber for the production of heating and combustion gases at moderate temperatures comprising a metallic cylindrical outer wall, and a metallic inner wall supported from the outer wall in concentric spaced rel-ation thereto and providing an annular gas space between the outer wall and the inner wall and a combustion space within the inner wall, said inner wall comprising a plurality of annular channels for the passage of cooling gas from said annular gas space through said inner wall into said combustion space, said channels being substantially coextensive with the area of said inner wall exposed toV the combustion flame in said combustion space.

2. A combustion chamber for the production of heating and combustion gases at moderate temperatures comprising a metallic cylindrical outer wall, and a metallic inner wall supported from the outer wall in concentric spaced relation thereto by means of iiexible link members permitting thermal expansion o! the inner wall and providing an annular gas space between the outer wall and the inner wall an'd a combustion space within the inner wall, said inner wall comprising a plurality of annular channels for the-passage o! cooling gas from said annular gas space through said inner wall into said combustion space, said channels being substantially coextensive with the area of said inner wall exposed to the combustion flame in said combustion space.

3. A combustion chamber for the production of heating and combustion gases at moderate temperatures comprising a metallic cylindrical outer wall, and a metallic inner wall supported from the outer wall in concentric spaced relation thereto by means of radial rib members horizontally movable in guideways to permit thermal expansion of the inner wall and providing an annular gas space between the outer wall and the inner wall and a combustion space within the inner wall, said inner wall comprising a plurality of annular channels for the passage of cooling gas from said annular gas space through said inner wall into said combustion space, said channels being substantially coextensive with the area of said inner wall exposed to the combustion flame in said combustion space.

4. A combustion chamber for the production of heating and combustion gases at moderate temperatures comprising a metallic cylindrical outer wall, and a metallic inner wall supported from the outer wall in concentric spaced relation thereto and providing an annular4 gas space between the outer wall and the inner wall and a combustion space within the inner wall, said inner wall comprising a plurality of overlapping` conical rings spaced to provide between said rings a plurality of annular channels for the passage of cooling gas from said annular gas space through said inner wall into said combustion space, said channels being substantially coextensive with the area of said inner wall exposed to the combustion flame in said combustion space.

5. A combustion chamber for the production of heating and combustion gases at moderate temperatures comprising a metallic cylindrical outer wall, and a metallic inner wall supported from the outer wall in concentric spaced relation thereto and providing an annular gas space between the outer wall and the inner wall and a combustion space within the inner wall, said inner wall comprising a plurality of overlapping stepped cylindrical rings spaced to provide between said rings a plurality of annular channels for the passage of cooling gas from said annular gas space through said inner wall into said combustion space, said channels being substantially coextensive with the area of said inner wall exposed to the combustion flame in said combustion space.

CLAUDE SEIPPEL. 

